It's not quite the same. Pre-JB we had voice search, but JB introduced Google Now, which is far better than a simple voice search - it learns. For instance, if you look for bus schedules while at home, when you are at a bus stop it will automatically pop-up the timetable for the next bus. It will know when you're on your way home from the office, and will give you an estimate of the travel time, and so on.

Does this require some new OS services that are only in JB, or can it be added to ICS as an app?

Does this require some new OS services that are only in JB, or can it be added to ICS as an app?

ApK

It can be hacked to work in ICS, but it genuinely needs JB. Google improved the voice algorithms and that's in the framework, so if you hack it to work on ICS (as some have done), it works, but the voice recognition capabilities are diminished.